Slashdot videos: Now with more Slashdot!

View

Discuss

Share

We've improved Slashdot's video section; now you can view our video interviews, product close-ups and site visits with all the usual Slashdot options to comment, share, etc. No more walled garden! It's a work in progress -- we hope you'll check it out (Learn more about the recent updates).

Smithsonian.com covers research that began with the study of birdsong and ended by overturning the common belief that adult animals can't produce new brain cells. "Deconstructing birdsong may seem an unlikely way to shake up biology. But [Fernando] Nottebohm's research has shattered the belief that a brain gets its quota of nerve cells shortly after birth and stands by helplessly as one by one they die — a 'fact' drummed into every schoolkid's skull. [Nottebohm] demonstrated two decades ago that the brain of a male songbird grows fresh nerve cells in the fall to replace those that die off in summer. The findings were shocking, and scientists voiced skepticism that the adult human brain had the same knack for regeneration. ... Yet, inspired by Nottebohm's work, researchers went on to find that other adult animals — including human beings — are indeed capable of producing new brain cells. And in February, scientists reported for the first time that brand-new nerves in adult mouse brains appeared to conduct impulses — a finding that addressed lingering concerns that newly formed adult neurons might not function."

Or rather, as my chemistry teacher told me in highschool, it's not the alcohol that damages your brain cells, it's dehydration during the hangover. Stay well hydrated and you can get as tanked as you like. Your liver may hate you but your brain will be fine.:D

Cliff expounds his "Buffalo Theory" to Norm:Well, you see, Norm, it's like this. A herd of buffalo can only move as fast as the slowest buffalo. And when the herd is hunted, it's the slowest and weakest ones at the back that are killed first. This natural selection is good for the herd as a whole, because the general speed and health of the whole group keeps improving by the regular killing of the weakest members.

In much the same way, the human brain can only operate as fast as the slowest brain cells. Now, as we know, excessive intake of alcohol kills brain cells. But naturally, it attacks the slowest and weakest brain cells first. In this way, regular consumption of beer eliminates the weaker brain cells, making the brain a faster and more efficient machine.

The whole "You only get so many cells" seemed counter intuitive to me. Logically it made very little sense. I never really cared though if it was true. I'm not a biologist nor did I ever do anything that would of required me to use such information.
I always thought that You only get so many cell divisions seemed more likely. After all cells don't replicate perfectly.

Take a june bug, large and green...tie a string to it's leg and let him fly in circles. At the point where he starts to BLUR, that must be the speed of light. Figure the scale based on RPMs, etc the usual way.

SO: Speed of light: 34 mph!

Seriously: this standard stood for something like 700 years. Science: imperfect.

Early, scientific attempts to measure speed of light were very... Well... scientific. And quite accurate. In 1021 an Iraqi physicist realized that light has finite, variable speed that is slower in denser bodies.

In 1629-1667 there were several tries to measure how long it takes for light to move two miles. They all however got to the conclusion that it couldn't be measured because light's spee

You know that female mammals only get one supply of eggs? Once their gone, their gone. Not really sure why the evolution god would give a women two million eggs....maybe they originally evolved to live for thousands of years. Or maybe we were only supposed to live 80 years, but have like 1.99 million kids. Or maybe early humans were like salmon with a 90+% infant mortality.

This is actually very awesome as we have slowly made use of mice/rat brain cells as computing devices. This adds a whole new level, Just imagine a self-repairing/expanding computer... hmmmm maybe that's not such a good idea.

So nobody read TFA? It is from 2002.
Research since then has shown that the mouse, rat and human hippocampus (specifically the dentate gyrus, the region that if destroyed produces antereograde amnesia, like in Memento) can grow new cells that replace old ones. This also happens in the olfactory bulb - a region that helps us tell the difference between similar odors.

I learned that nerve, fat, and muscle cells didn't change in number during life*. Seems that's not true about neurons. Apparently also not true about fat cells [wikipedia.org] ("If excess weight is gained as an adult, fat cells increase in size about fourfold before dividing and increasing the absolute number of fat cells present.") Anyone know the scoop on muscle cells?

* - Supposedly weight gain was due to the individual adipocytes getting larger, like a microcosmic obesity. And strength gain was due to more actin and myocin in each myocyte, like a micrcosmic bodybuilder.

Blasphemy! Each person only has 1 muscle cell that grows larger as they work out./s

I learned the same things in school myself. We ere even taught that nerve cells didn't get repaired after they were damaged (to the point of dying). Oh, except in the tongue. Those were unique for some reason. And then we started learning that other nerve cells (like in the spine) did sometimes heal, but that perhaps the 'muscle memory' was lost, and learning to walk when you are an adult is much harder than it was as a child. At some point I think we may just have to say, "We don't know what we think we know, and maybe we should just start all over again." We stand on the shoulders of giants when we discover something new, but apparently sometimes it turns of those are midget's, not giant's shoulders, and we are forced to unlearn something we thought was true. Thus goes the ways of science.

Each person only has 1 muscle cell that grows larger as they work out.

Ah yes, the love muscle...In most slashdotters this is pretty well atrophied from disuse - at least until the pics of a statue of a naked natalie portman covered in hot grits shows up on the intertubes.

Despite its eternal popularity, this quote doesn't connote meekness or high hopes for scientific progress. When Newton spoke these words he did so not because he felt star-struck or humble, but so might he insult another scientist who happened to be a midget.

So stop quoting it like some sage wisdom out of scientific history. Please.

Why Newton said it is completely irrelevant -- the sentiment is interesting, inspiring and useful in its own right, and that's why it has survived on its own right, not as sage wisdom out of scientific *history*, but sage wisdom out of scientific *tradition*. It should not be judged as a "quote" based on its origin, but as a saying, based on how people mean it today, in which case you're entirely wrong -- the saying *does* connote meekness and high hopes for scientific progress.

This is what I was told when I was a runner. The physical therapists had massages that would create tons of pain, but explained that the reason for this pain is they were creating new tears and expanding the ones caused by the work out while at the same time pushing lactic acid out of the muscle. Flushing out the lactic acid was supposed to help the rips heal faster (I have no idea if that part is true or not).

No. That it outdated knowledge and is actually an overworking of your muscles. I know that it's stated again, and again, and again, by people who seem to be experts by all standards. Yet there is proper proof that it's not the right way to get stronger, and actually creates scar tissue. So you might get bigger muscles, but not really stronger ones! The strength comes from the tissue that did *not* rupture,and was allowed to grow.

So it's better to lift a lighter weight more often, than a heavier one just a couple of times.

Isn't that a contradiction in terms? If it's wrong now, it was just as wrong when it was being taught... knowledge doesn't get "outdated". Opinions and beliefs and fashionable ideas may change... but not actual *knowledge*.

Pedantic, I know, but I get creeped out by the subtle assumption that somehow the very foundations of reality change under us as the scientific consensus shifts. This sort of abuse of language and the misidentification of beliefs, teachings and opinions with fact, is exactly why the man in the street has grown to distrust "science".

I'm pretty horrified myself if this "muscle tearing" thing is in fact incorrect - because that's what I was taught in high school gym class. It sounded stupid and abusive to me at the time - why should destroying muscle be a *good* thing? - and it was used to justify the "if it doesn't hurt you're not doing it right" idea. If it turns out that that was a flat lie all along... yeah, I'm pretty pissed off. Shouldn't we hold off making *any* such "scientific" pronouncements until we're darn sure, for good and all, that we're NOT just saying crazy wrong things?

I mean, the current accepted philosophical basis of science is Karl Popper's falsifiability criterion, which is not a monotonic logic... yet we don't have anything like a universally accepted formalisation of nonmonotonic logic [stanford.edu] to deal with this kind of situation (where something believed 'true'at time A becomes 'false' at time B when new facts emerge). There's no standard way of dealing with this in logic - much foundational work was only *started* in the 1980s and the results are still very unclear. So t

If you look at the history of "modern science", from circa Newton and forward, the hard science has been separated from philosophy.

In a way you can say that the philosophers are constantly trying to catch up, and integrate the new knowledge in their world perceptions.

As a whole I do not think that is a problem. We might occationally stumble upon a field or a method that we in hindsight can see was a bad idea, for ethical reasons, but the checks and balances that is built into academia and s

In a way you can say that the philosophers are constantly trying to catch up, and integrate the new knowledge in their world perceptions.

Only the analytical philosophers, and that's because they limited themselves to "reality," and as such, since reality is best defined by science, they're limited by what science says it reality is.

Philosophy doesn't require science; it is much more vast, much greater, than science. The universe itself (of which science is mainly regarding) cannot encompass all the possibilities of thought. Science, or really, the scientific method itself is a philosophy of truth.

So it's better to lift a lighter weight more often, than a heavier one just a couple of times.

People differ. I've had more gains from "one max rep" style workouts (where you start at the heaviest weight you can do a single rep with and work down) than anything else. Anyone who believes there is one single optimal workout for all people is ignorant of the real, empirical variation between individuals and not qualified to give workout advice.

As someone who is tall, slim and has relatively long and narrow muscles, I've always profited most from the "lots of reps with light weights" approach. I don't seem to accumulate any more muscle mass, my weight stays pretty much the same but I can squeeze out a lot more performance from the same muscles without the downsides of lots of actual muscle mass(and without the upsides of looking ripped, if there are any).

Also, there are different gains from different types of set/rep combinations. Tons of professional strength athletes and body builders can attest to this being true, even if the mechanics behind it are a bit fuzzy. If you do 5 sets of 5 quick lifts with a good pause in between sets, you force your body to adapt to that intensity and duration, building mostly explosive strength and some mass. If you do 1x15-20, lifting slowly on the negative (4-6 seconds) you build more mass than explosive strength. You of c

So it's better to lift a lighter weight more often, than a heavier one just a couple of times.

I don't know where you get this from but it's complete and utter bullcrap. Your statement alone is incomplete at best, with references to 'lighter weights', 'couple of times', it does not get any more vague than that. Don't listen to this folks, weightlifters don't exclusively do lighter weights and many repetitions simply because it is not optimal for pure strength. If you lift weights regurarly following a program even only for one year, you will know from experience that you need to stress and overload y

So it's better to lift a lighter weight more often, than a heavier one just a couple of times.

No, the only thing that lifting lighter weights more often will give you is the ability to lift light things many times. That's called endurance. Lifting heavy things less often will give you the ability to lift heavy things. That's called strength. Which one is "better" for you depends on your fitness goals.

The new cells come from myoblasts that differentiate from satellite cells that exist in the muscle tissue. The damaged muscle cells release signals that cause the satellite cells to do this. The myoblasts in turn develop and fuse together to form the mature multi-nucleated myocytes. In addition to forming myoblasts, the satellite cells also divide to replenish (to a limited extent) the satellite cells that turn into myoblasts.

And it has been known for several years that neuronal stem cells exist in the

Muscle cells form long fibers but don't generally get "fatter" the way fat cells do. You can both gain and lose muscle cells depending on circumstance.

It's true that fat cells can grow and shrink as they are "filled". But laying new cells when you eat a lot is almost entirely a one-way process. When you lose weight the cells lose their stores, but don't disappear. This could be why it's easier to gain weight than to lose it, or why really fat people that lose hundreds of pounds have this flab that ne

Cells generally respond to being overworked by either hypertrophy (increase in number) or hyperplasia (increase in number). Realistically, most cells do both, although one method may dominate. Some Googling reveals that hyperplasia definitely happens in human smooth and cardiac muscle, and probably happens to some extent in skeletal muscle (animal studies demonstrate it). As far as neurons go, your olfactory neurons (responsible for smell) are actually constantly dividing as well (turn-over time of a cou

Like everything else, it probably varies with person. My strength has increased about 50% in the past nine months (check out the Big Five workout and the book "Body By Science"--best workout I've ever used.) but my bulk has hardly increased at all--I'm a hard gainer.

This is also true of the brain, as anyone who has studied anything about strokes in the past 20 years (since the advent of CT) has known: some people have highly plastic neurological function, so the destr

Of course they are able to "grow" and remap themselves. What is generally taught is that they do not generally divide to replace dead or damaged nerve cells. If you cut away a piece of skin, the cells in that area divide until the wound if closed (or that's the way it's supposed to work, at least). If you kill a piece of your brain, there is (according to general "knowledge") no way to regenerate these lost cells.

I don't mean "duh" to the researcher -- obviously things must be tested and validated in the real world, not just postulated -- but it never made sense to me in the first place that brain cells can't regenerate. Why the hell not? What is the adaptive purpose of such a limitation? The brain consumes a huge amount of energy, much more so per-pound than any other organ in the body. That seems to imply that the brain is extremely important to the organism. Why would essentially the most important organ in the body have such a stupid limitation that it can't even recover from MINOR damage? That makes no sense.

One possible explanation for the very limited growth rate of brain cells is that if this growth rate were not tightly controlled, it could lead to "chaotic" brain tissue which could interfere with normal brain function. So general division of brain cells would not be desirable -- but I'm no neuroscientist.

Cancer is the uncontrolled division of cells. I could see an evolutionary incentive to stop all (or most) cell division at some point, so that the cells that are dividing (cancer) can be controlled and eliminated by the body.

I don't mean "duh" to the researcher -- obviously things must be tested and validated in the real world, not just postulated -- but it never made sense to me in the first place that brain cells can't regenerate. Why the hell not? What is the adaptive purpose of such a limitation? The brain consumes a huge amount of energy, much more so per-pound than any other organ in the body. That seems to imply that the brain is extremely important to the organism. Why would essentially the most important organ in the body have such a stupid limitation that it can't even recover from MINOR damage? That makes no sense.

One possible explanation for the very limited growth rate of brain cells is that if this growth rate were not tightly controlled, it could lead to "chaotic" brain tissue which could interfere with normal brain function. So general division of brain cells would not be desirable -- but I'm no neuroscientist.

I am, and you're right in nearly every detail. I'd only add:

- New growth would consume energy that the very hungry brain would prefer not to waste that way.

- Brain function develops by strengthening some of its connections, but losing far more. You're born with 4 times the connections you die with. There's no need for new cells in terms of function.

- It actually is in repair that 'chaotic' growth occurs. Neurons are notoriously stupid when it comes to regrowing back in the same place. Severed nerve trunks try to grow back together but get tangled and miss connection, make incorrect connections, or simply turn back on themselves in a tangled "stump neuroma". Some (but not all) of this occurs because the 'interneurons' that act as the telephone poles to the neural wires also get damaged and/or die.

- There's good progress made in getting neurons to regrow and reattach properly, using techniques of treating the cut nerves with certain things and/or using host stem cells. I'm not fully up on the details, but I will be once I read a copy of my son's dissertation; he defended it last month and is just finishing the revisions. I do know that in some cases even severed spinal cords could grow back correctly enough for partial function if treated soon enough with a particular substance. That substance is a common food additive, so phase 1 clinical trials might be skipped. The hope is an injectable treatment would be available to emergency workers which, if the testing bears out the initial studies, would give people with severed nerves more than half their original function in more than half the cases.

I do know that in some cases even severed spinal cords could grow back correctly enough for partial function if treated soon enough with a particular substance. That substance is a common food additive,

I do know that in some cases even severed spinal cords could grow back correctly enough for partial function if treated soon enough with a particular substance. That substance is a common food additive, so phase 1 clinical trials might be skipped.

You may have ethical reasons for being vague about what exactly this "substance" is, but given what you've said here, I'd wager you're talking about glutamate?

I do know that in some cases even severed spinal cords could grow back correctly enough for partial function if treated soon enough with a particular substance. That substance is a common food additive, so phase 1 clinical trials might be skipped.

You may have ethical reasons for being vague about what exactly this "substance" is, but given what you've said here, I'd wager you're talking about glutamate?

Glutamate is a transmitter precursor, not a growth promoter.

I didn't know whether the news was out about this stuff or not so I had to find out first. Turns out I'm way late in catching up on my son's work. The Wikipedia page on this stuff references a 2001 study done at Purdue; that was the lab he worked in as an undergrad.

See this BBC News article from 2000 [bbc.co.uk] which describes how, "part of the hippocampus grew larger as the taxi drivers spent more time in the job." Navigating the streets of London for a job requires more spacial memory and reasoning so that bit of the brain grows.

Um, what? You say that like it's a bad thing. I bet you also call politicians "flip-floppers" and say they have "weak leadership" when they change their policies based on global and local events. There's a place for unquestioning adherence to the status quo, but that place is not in scientific research.

I don't see why the parent post was rated "Troll", nor do I understand the other replies to it. The parent is expressing that "There's hope for us yet." We can hold very entrenched scientific ideas, but are not unwilling to discard them when presented with evidence of their falsity. This is a good thing, and I think the OP was just pointing it out.

So a scientific view that is considered the "settled" "consensus" view can change in the face of contrary evidence? That's good to know.

That's exactly correct. That's precisely how science works, and it wouldn't work any other way. When you continue to believe something in the face of contrary evidence, that's called being (1) irrational, (2) stupid, or (3) both. Had you paid attention when the teachers were trying to explain this, you wouldn't be (1), (2) or (3).

But I will add that, as noted below, just because you're (1), (2) or (3), you're only wrong, not trolling. Someone who mods a comment down just because it's wrong is both (2), and

The history of science is full of consensus breaking ideas. Science is a discourse, not a religion. The only sacred truth is that there is no sacred truth. The consensus, however, can only be broken by _evidence_. So creation scientists and AGW deniers are out of luck.

Don't get too excited yet. As the article states in humans the only well-established generation of new nerve cells occurs in the hippocampus, a structure which conveniently is involved in memory.

There was another study dating cells based on inclusion of radioisotopes left over from atmospheric nuclear weapons testing, apparently finding a very slow rate of new cell generation, measured in something like percent (or fraction thereof) per decade of the total. And their study only holds true if they correc

It's amazing how strong many scientists believe in certain things that are not even theories, and have a hard time changing their minds in the face of evidence to the contrary. We saw it with 'junk DNA' (long strands of DNA between genes that apparently had no purpose, so scientists decided it must be junk left over from evolution), stem cells, and now the dogma that certain types of tissue can't regenerate. Luckily they are proven wrong time and time again, which keeps biology exciting and opens new possib

It's amazing how strong many scientists believe in certain things that are not even theories, and have a hard time changing their minds in the face of evidence to the contrary.

Why should we scientists be any different from the rest of you? We're people acting like people do, we just happen to be trying to figure things out in public. Besides, we have to believe something as a starting point so we can test an idea, and when we do have evidence, develop a theory which we can then further test to find out where we're wrong, discard that, and repeat the process. A science example of this is solar neutrinos. Despite many well designed experiments using well tested devices, only one th

Fact is, regeneration of brain cells is very, very, very, very limited. In the case of severe brain injuries, it basically doesn't happen. (the reason recovery is possible is due to rerouting around the damage by cannibalizing existing cells). This depressing fact has been well known to neurologists and neurosurgeons for at least 50 years. Now, as it may turn out, there actually IS a little bit of regeneration. That doesn't change the fact that even if it happens a little bit, for all practical purpose

Take the example of a Hemispherectomy. A huge portion of the brain can be disabled, and depending on the patient, relatively few complications result.

Think about the redundancy built into that system that would be necessary for this to happen.

What depresses me is the notion that brains aren't going to get better. It seems more like, if we could remove the damaged portion another would eventually take over. Coupled with this new 'new brain cell' information, now I'm wondering if we should be trying to fin

<flame>I beg your pardon? You admit not knowing who came up with that idea, and that you have no idea what evidence they had for their claims; that is, you have no idea at all what the fuck you are talking about, and yet you somehow think you have the right to imply scientists who are no doubt far more knowledgeable when it comes to (neuro-)biology than you are should not have been taken seriously. You, sir, are an asshole.</flame>Guess what. If you seriously damage some part of your brain, it w

scientists who are no doubt far more knowledgeable when it comes to (neuro-)biology than you

Haha... except the bit where they had wrong what I had right.

Guess what. If you seriously damage some part of your brain, it won't (significantly) recover. If that part of your brain was responsible for some function, you will either lose that function, or other areas of your brain will (partially) take over that function or compensate in some other way. If you damage your spinal cord you may never fully recover. Eve

I disagree - ridicule is a powerful way of socially marginalising people and discouraging other people from taking them seriously. God (in the common religious sense, not the abstract philosophical sense) has been unable to fit in our current scientific knowledge about the world for quite some time, but this has not stopped nonsense from being believed. While it is important not to stoop to dishonesty and etc, all those who are scientific leaders of a kind have to be forceful in calling out folk who peddle